
When I'm trying to run the cd command on my virtual pc is shows error as shown in pic above. How can I change the directory?

When I'm trying to run the cd command on my virtual pc is shows error as shown in pic above. How can I change the directory?
You simply misspelled it: In Ubuntu (and generally in Unix systems), file and directory names are case-sensitive and the directory's name is Desktop:
cd Desktop # if you are in your home directory (relative path)
cd ~/Desktop # if you are anywhere else (absolute path)